1. Field of the invention
This invention relates, generally, to surgical tools. More particularly, it relates to a surgical tool that expands an opening initially formed in a body cavity by a trocar.
2. Description of the Prior Art
Surgery often begins with the making of an elongate incision. As is well known, healing of such incisions requires a lengthy recovery time. A trocar is therefore sometimes used in those situations where an incision can be avoided.
A trocar is a sharp-pointed surgical tool used to pierce a body cavity, such as the abdominal cavity, for example. More particularly, a trocar is a straight metallic rod having a pointed leading end that forms a puncture opening of substantially round shape. A surgeon can then perform surgical procedures through the puncture opening, thereby avoiding a conventional incision and reducing the post-operative recovery time for the patient.
The puncture opening is held open by a cannula that is carried by the trailing end of the trocar and which remains in place when the trocar is withdrawn; the cannula may serve as a drainage outlet. It may also serve as a passageway for the insertion of surgical tools such as used in arthroscopy and laparoscopy.
Since the advent of miniature cameras and fiber optics, the cannula may also be used as a passageway for insertion into the body cavity of a camera and lighting means so that a physician may view the interior of the cavity.
For example, it is possible to remove a gall bladder by using a conventional trocar, but only if the diseased gall bladder is small enough to be retracted from the body cavity through the cannula. If the gall bladder is too large to be pulled through the passageway defined by the cannula, then the initial puncture opening must be enlarged by means of a conventional incision.
What is needed, then, is an improved trocar that is not subject to the limitations of conventional trocars.
However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in this art how the art could be advanced.